1. Field of the Invention
The present invention relates to a method of fabricating a cartridge type filter for adsorbing and removing the component solved in water or aqueous solution to be purified, and more particularly to a molded filter element having two kinds of functions of filtering and adsorption.
2. Description of the Prior Art
In recent years, with an increase in used amount of water, deterioration of water quality has become problematic. In order to solve this problem, usually, the water has been filtered using a water purifier and a small amount of impurities contained in the water has been adsorbed and removed. In industrial use also, cleaning water of a high degree of purity has been required in many cases. The adsorbent in the water purifier used for water purification has been usually used as a cartridge type in which granular activated-carbon and/or zeolite are filled in container such as a tube-like case or sack.
However, the adsorption unit of the filling cartridge type is likely to have a non-uniform filling density so that it causes "channeling" during filtering, thus providing insufficient adsorption capability. As the case may be, the following accident is likely to occur. Namely, while the adsorbent is used, the purified water may be polluted by powder which flows out because of the collapse of the adsorbent.
In order to obviate such a defect, an adsorbent unit has been proposed in which nonwoven cloth of activated carbon fiber is wound around a porous hollow-cylinder. Although this adsorbent has advantages of uniform opening or space rate and adsorption force and less fluctuation, it has disadvantages of large bulk, small adsorption capacity per volume and high production cost.
In Japanese Utility Model Laid-open No. Sho 60-91216 (1985), a filter element has been also proposed, in which the inner and outer surfaces of a cylindrical porous adsorption material are covered with an adsorbent fiber layer and filter cloth (The cylindrical porous adsorption material can be made by thermally molding mixed adsorption particles and thermally-soluble fiber). Such a porous adsorption material, however, has disadvantages of complicated structure, difficult control of the opening rate and high production cost due to use of particular materials.